Justyna Kędziorek, Michalina Błażkiewicz, Katarzyna Kaczmarczyk
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引用次数: 0
Abstract
Purpose: This study examined the use of nonlinear measures - sample entropy (SampEn), fractal dimension (FD), and the Lyapunov exponent (LyE) - to evaluate postural control in adults during standing on an unstable surface, with and without visual feedback.
Methods: 14 healthy young adults (24.07 ± 7.32 years) completed bipedal standing trials on an unstable-plate Biodex Balance System (BBS) connected to a Vicon system, with eyes open and closed. Each trial lasted 20 sec. Analysis was performed based on the center of mass (CoM), for which the three nonlinear measures were calculated.
Results: Excluding visual feedback was found to cause a significant increase in linear and nonlinear parameters. Moreover, SampEn and FD values were found to be significantly higher in the PD direction, compared to AP or ML, whereas LyE values in this direction were minimal.
Conclusions: Results show that the three nonlinear measures provide a useful way of evaluating postural control in healthy adults. Moreover, it seems that introducing an unstable surface meant that the projection of the CoM was not perpendicular to the surface, but rather set at a certain continually changing angle, forcing the whole system to adapt to chaotic and unpredictable conditions. Such refined changes in conditions can be evaluated in a precise way only by using nonlinear measures.
期刊介绍:
Acta of Bioengineering and Biomechanics is a platform allowing presentation of investigations results, exchange of ideas and experiences among researchers with technical and medical background.
Papers published in Acta of Bioengineering and Biomechanics may cover a wide range of topics in biomechanics, including, but not limited to:
Tissue Biomechanics,
Orthopedic Biomechanics,
Biomaterials,
Sport Biomechanics.